# CVE-2026-55149

## Summary

- **CVE ID:** CVE-2026-55149
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** CWE-789
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 17, 2026

## Description

Vouch Proxy is an SSO and OAuth/OIDC login solution for Nginx using the auth_request module. Prior to 0.48.0, Cookie in pkg/cookie/cookie.go parses the total part count from an attacker-controlled multipart cookie name and passes the value to make([]string, numParts) without checking that the value is positive or reasonably bounded. Requests to /validate and /_external-auth-:id reach JWTCacheHandler in pkg/jwtmanager/jwtcache.go, FindJWT in pkg/jwtmanager/jwtmanager.go, and the vulnerable cookie reassembly before JWT validation, so no account or valid session is required. A cookie name such as VouchCookie_1of10000000000 causes an attempted slice allocation of roughly 160 GB and a fatal Go runtime out-of-memory condition, allowing one request to crash the authentication proxy and repeated requests to sustain unavailability. This vulnerability is fixed in 0.48.0.

## Affected Products

- vouch — vouch-proxy (< 0.48.0)

## References

- [CNA](https://github.com/vouch/vouch-proxy/security/advisories/GHSA-qqff-5854-px68)
- [CNA](https://github.com/vouch/vouch-proxy/commit/fa18ce30ba50a4863a436acad044c22965329c4f)
- [CNA](https://github.com/vouch/vouch-proxy/releases/tag/v0.48.0)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.40%
- **EPSS Percentile:** 33.6

---
_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._